The AT Commands

The AT commands are a group of special commands recognised by your modem. These commands derive their name from the letters AT, which are used to prefix commands. Before continuing:

Run your communications software and enter local mode (or terminal mode) at 38,400 bps Refer to your communication software manual for details.

The Attention Code

An AT (sometimes known as the ATtention code) usually precedes all commands being sent to the modem. It is used to gain the modem’s attention, informing it that you are about to send a command. For example:

Type the command: ATI9 <E>

Your modem’s firmware identity message will appear on your computer screen. If you type I9 only, your modem will not respond. If you type AT19, your modem will report an ERROR.

You may enter the attention code in all upper case, or all lower case letters, such as: AT or at

Multiple Commands

You may place multiple modem commands after an AT provided the total number of characters does not exceed 80. For example, a valid command to display the modem’s firmware identity twice is:

Type in the command: ATI9I9 <E>

An AT is not required in front of the second I9 command. You only need one attention code for each command line. To make this command more readable, you can add spaces between the two commands:

Type in the command: AT I9 I9 <E>

The modem will execute the command as if the spaces are not there.

The Escape Sequence

When you issue commands to the modem all dialogue is occurring between your computer and the modem. This situation is known as local command state.

When you connect to a remote system, dialogue will be occurring between your computer and the remote system. This is known as on-line state. Because the modem assumes, after it enters on-line state, all the data you send it is to be sent on to the remote modem, it ignores any AT commands you give it while in on-line state.

To force the modem to return to local command state, enter an escapesequence. An escape sequence consists of a one second delay, three + characters typed rapidly and another one second delay. For example:

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Telenetics 56 manual AT Commands, Multiple Commands, Escape Sequence